"Biroudo-tentsuki" (Fimbristylis sericea) belongs to Cyperaceae (the Sedge family). It is a perennial herb that is distributed westward from Kanto district of Honshu to Shikoku and Kyushu of Japan, the Korean Peninsula, Taiwan, eastern China, Southeast Asia and Australia. This herb grows in sandy soiles on the beaches and can reach 10-30 cm in height. The rhizomes are thick, short and covered with dead sheaths. The leaves are linear and clumping. The stems and leaves are covered with white velvety hairs. The 3-15 spikelets are borne on the stem apices and bloom inconspicuous flowers from August to October.